Find the requested composition of functions.
-Given $f ( x ) = x ^ { 2 } + 9$ and $g ( x ) = x ^ { 2 } - 9$, find $f \circ g ( x )$.
A) $x ^ { 4 } - 18 x ^ { 2 } + 72$
B) $x ^ { 4 } - 18 x ^ { 2 } + 90$
C) $x ^ { 4 } + 18 x ^ { 2 } + 72$
D) $x ^ { 4 } + 18 x ^ { 2 } + 90$

Question

Quizplus · Accepted Answer

To find $f \circ g ( x )$, substitute $g(x)$ into $f(x)$: $f(g(x)) = (x^2 - 9)^2 + 9 = x^4 - 18x^2 + 81 + 9 = x^4 - 18x^2 + 90$.

Find the Requested Composition of Functions f(x)=x2+9f ( x ) = x ^ { 2 } + 9f(x)=x2+9

Find the Requested Composition of Functions $f ( x ) = x ^ { 2 } + 9$